What is resonance?

Each time a Quest is completed with an esper equipped, the resonance between the esper and the unit it was equipped to will increase. As resonance increases, you will receive the following bonuses:
• The unit will receive a stat boost
• The effect duration of any Evocation Magic that induces map effects will increase

*Tap the Resonance button on an esper's Details screen for more information on its resonance with different units and resonance bonus effects.